Chain guiding device for portable motor tree saws



April 11, 1933. w, MEYER 01mm GUIDING nsvxcn FOR Penman: mo'roa mm SAWS 2 Sheets-sheaf. 1

Filed Jan. 8, 1932 F. w. MEYER 1,903,571

CHAIN GUIDING DEVICE FOR PORTABLE MOTOR TREE SAWS April 11, 1933.

2 Sheeis-Sheet 2 Filed Jan. 8, 1932 the shipment of which turns while the saw advances.

- PM A... n, ma

IBIEDBIGE' m OI VIHKA, AUSTRIA.

mm ammo nnvicn Ion. ron'ranm Moron ma saws 1 Application Med January 8, 1988. Serial No. 885,834, and in Austria January 18, 1981.

tor tree saws, in w ich t e saw chai n,is

guidedon a rail and is tightened by means 5 of a special tightening device cooperating directly or indirectly with this rail.

In general these guiding rails are directly fixed to the motor body, this construction, however, entailin the disadvantage, that e machine and the transort to the lace of operation meets with difculties. f, on the other hand, the rail is dismounted for transport and is not refastened to the motor body before the working place is reached and operation is about to start this means a very disagreeable extra wor especially since in eve case the saw chain must be mounted and dismounted too. Accordingto the invention the rail is '20 not directly fixed to the motor body but to a separate part, preferably a cover, which, for

the driving members of the chain, can be screwed on to the machine body and unscrewed from same in a simple manner. The gear wheel, driving the-chains is 'journalled in the cover and is provided with'entrainer claws which in placing the cover on the ma* chine engage into the correspondingclaws a of the free end of the motor shaft. The chain 1 'always remains mounted whether the cover is being screwed on or being removed. .The cover also serves as protectlng device (guard).

' The cover may be formed into I a stop against which the working piece comes to rest during the sawing process.. In order to eliminate the friction eventually arising between the stop and the working piece during the advance of the saw and in order to be able to put the saw to work comfortably even with an oblique direction of the cut, the stop is replaced or completed by a supporting rollof roughened or toothed surfslilce T is sup orting roll may also be fixed to the motor ody instead of to the cover.

With a view to enable the saw to carry out upward directed cuts too, the other end of the rail i. e. the handle end is also furnished with astop or a supporting roll. In this case the iece of wood worked on, will rest against t e stop above the rail.

A further feature of the saw guiding device accordin to theinvention resides in the manner in w ich the tightenin operating with the rail is forme rendering possible an easy mountin of the chain on the rail i. e. on the chain w eels supported by device cosame and warranting an accurate guidance of the chain wheel which is displaceable in aknown manner by means of a tightening device. In the known designs of this kind (German Patent 477,190) a chain wheel is rotatablly supported by a bolt at the end of the gui e rail, the bolt passin vlong1tudinal slots of the for shaped rail end (rail head) and being supported at both ends in bearin s fixed in the guide bars of a tightening bo y provided with handle and spring, the said uide bars beingxlon tudinally displaceab e over the for By turning the handle, which is screwed on to the tightening device, round its longitudinal axis the s ring isput under tension, and

the toothed c ain wheel is dis laced in the 7 direction toward the end of t e (guide rail,

; whereby the saw chain is tightene The guide bars of the tightening body used in this device known are made of channel through two irons. Their machining as well as that of 90 the corresponding shaped parts of the fork ends presents great difliculties and it is scarcely possible to produce same with the accuracy required for realizing an exact fit. In this device the ends of the chain wheel bolts do not rest on the sliding surface of the fork ends, face to face, but, theoretically, are in touch with same along a line, a feature which is disadvantageous with respect to the accuracy of the guidance and the duration of the device. The mountin and the dismounting of the device is difiicu t as, firstthe chain wheel must be held suspended between the fork ends of the guide rail; then the guide bars of the tightening bod are slipped over the fork ends and are a iusted in such a manner that the pillow blocks of the guide bars are made to coincide with the axis of the toothed wheel; finally the chain wheel bolt is inserted. As, for this method of of time.

The resent invention permits to do awa with a these drawbacks. First of all, bet the outer surfaces of the fork ends of the guide rail and the inner surfaces of the guide bars oi? the tightening body are formed cy- .lindrically so that the sliding surfaces of the fork ends as well as the sliding surfaces of the ide bars may be produced by turning on t e lathe, a process which is far cheaper and can be carried out with a far higher degree of accuracy than the machining of channel-shaped orrectilinear profiles. it is also possible, however, to formthe fork ends of the guide rail and the guide bars of the tightening body into hollow cylinders giving a sliding fit so as tobe longitudinally displaceable with respect to one another. The sliding slots for the chain wheel bolts are made in the walls of'the inner hollow cylinder. Besides both hollow cylinders are-provided vertically with slots of adequate size "for receiving the chain wheel and the chain.

For facilitating bbth mounting and dismounting, the chain wheel bolt is made so short that it does not project beyond the outer wall of the inner hollow cylinder viz. the fork ends; the ends of the bolt being tapped i. e. provided with inner threads, for the purpose of fastening the bolt to the outer hollow cylinder viz. the guide bars of the tightening body. For assuring a face to face resting of the ends of the chain wheel bolts in the sliding slots of the inner hollow cylinder viz. the fork ends, the ends of the bolts are flattened on both sides; but the one end more than the other, so that, in consequence,

the sliding slots of the inner cylinder viz. the iorlr ends are of different width. In this manner it has been made possible to laterally insert the chain bolt with the thinner end through the wider slot. The journal or pin on which the chain wheel runs between the bolt ends is of such a size asto permit its paning through the wider sliding slot.

A further improvement of the guiding device has been found in that an oil pump is nor an excessive consumption of oil during the intervals of work.

In the invention is illustrated by way of anexample, Fi 3. being a side elevational view of the guidance device attached to a motor, Fig. 2 a plan of same when detached from-the motor both figures bein schematic illustrations; Fig. 3 is a lcngituinal section throu h the handle with the tightening device and t e oil pump, Fig. 4a section through a part of the tightenin device along the lineA B of Fig. 3 and h ig. 5 a section along the line U-D of Fig. 3. The guide rail 1 is attached to the cover 3 by screws 2, the cover itself being fastened to the motor body 6 by means oi two screws 4: and 5. The driving ear wheel '8' for the saw chain is journalle in the cover and provided with entrainer jaws 8 gvlllich in mountin the cover on tclhe motor 0 y will engage in thecorrespon ing 'aws of the free end tied the motor shaft. llhis shows that the saw chain need not be recutting operations in the upward direction.

In this case the worlrin iece de a resting place at the stop 13 o handle 12 above the rail. The guide rail is riveted in between the flanges 14: and 15 oi the guide body 16. The bod id is a cylindrical hollow. body outward y machined on the lathe and fitted with two horizontal sliding slots 17 and 18, the slot 1? being hi her (i. e. wider) than the slot 18 (Fig. 3). esides, the hollow cylinder is provided with two vertical slots 19 and 20 covering the whole length, the widths of w ich correspond to the w1dth of the chain wheel and in which the chain wheel can move to and fro. The ri ht end of the idle body 1611s formed into a ollow, c lindrical projection 21 which is also vertlcall coincidin with the width of the saw chain.

Over t e uide bod. 16, which has the shape of a ho ow cylin er a ti htening body 231s slip ed which is a so ormed into a hollow cy nder, provided with two eyes 24 and 25 and with two vertical slots 26 and 27 assuring the mobilit of the chain and-the chain wheel. The tightening body23 projects into a hollow cylinder 29 the outer surface of which is threaded. The chain wheel bolt 30 .is formed in the middle into a round i. e. cylindrical running surface drawings an embodiment of the lid slotted at 22, the width of the slot I of the inner gui e body 16 which is hollowandcylindricelly shaped.- For fastening the bolts to the tightening body 23, the bolts are tapped i. e. provided with inner threads, the

tag screws 34, 35 being used for fixation.

he handle 36 is screwed to the projection 29. The interior of this handle holds a spring 37 which on one'side rests on the plug- 38 of the projection 210i the body 16 an presses on the other side against the bottom 39 of the handle 36., By rotating the handle round its axis the spring 37 is put undertension, causing the ollow body 16 and the 50 tightening body 23 to move asunder, whereby the chain is tightened.

The chain is mounted on the" guiding device in the following manner. The chain wheel 31 is introduced from above through the slot 19 of the hollow body. 16 and is held in this position with one hand. Then the bolt is introduced with the other hand from one side (i. e. from the right hand side with reference to Fig. 5) and passed 0 through the bore of the gear wheel until the two flattened ends 32 and "33 of the bolt are resting in the pertaining sliding slots 17 and 18 of the hollow body 16. Then the closed saw chain is introduced according to Fig. 3

5 from right to left through the vertical slot 22 of the projection 21 and placed on the chain whee Then the plu I 38 is stuck on. Further, the tightening bo y 23 is slipped over the hollow body 16 until the eyes 24 .0 and 25 are opposite-the bolt center. Then the two tap screws 34 and 35 are screwed in and tightened. Finally the handle 36 with the spring 37 already on the projection and turned until the chain 6 is sufliciently tightened. The chain wheel 31 which is driven by the saw chain 40 runs onthe bolt 30. The chain wheel 31 is provided with an eccentric, ring shaped groove 41 into which the. iston 42 is made to en- 0 gagle. Laterally, t 0 piston fits the. groove tig tly, whilst t is ressed against the bottom of the .groove hymeans of a spring. Owing to the eccentricity of this annular groove, a hollow space 44 is formed, which 5 by rotating the chain is made to wander round the bolt 30. hollow space is alternately filled with oil out of the oil tank 28 through the channels 45 and 46 and emptied again by the channel 48. This al- 0 .ternatin pressure and suction effect is caused y the hollow space gradually increasing when it reaches thepiston in the course of the rotation, so that a vacuum is builtup; whilst the ace havin arrived in 5 front of the piston wi continua y decrease inserted is screwed change of such units.

in volume so that the oil is pressed out of it. It is advantagious to provide the channel 48 with a sum is opened b the oil ressure, whilst it keeps the channe closed uring the standstill periods so that no oil can escape.

Having thus described my invention, I claim:

1. In portable motor tree saws, in combination a guiding device for the saw chain consisting of a gllide rail, two chain wheels, and a chain ti tenin device fixed on the outer endof t e gui e rail and having a handle, said tightenin device consistin of two hollow cylinders isplaceable one within the other, the outer cylinder having a tube shaped end, theinner cylinder bein fixed to the guide rail and bein fitted wit guiding slots and with a bolt or the outer chain wheel having flattened ends, said bolt being fixed to the outer cylinder; the inner cylinder having a projection protrudin into t e tube shaped end of the outer cyhnder, the handle bein adapted to be screwed on said tube shagefend, a spring arranged between the sai r the handle for t e purpose of tightening the chain bypushing asunder the inner cylinder fixed to the guide rail and the outer cylinder fixed to the outer chain wheel by turning the handle. Y

2. In portable motor tree saws, a guiding device for the saw chain as in claim 1,' in, which the displaceable cylinders .and the projection of the inner cylinder are vertically slotted, the slot of the projection reaching to its end, to permit inserting the wheel and the chain. c

3. In portable motor tree saws, a guiding device for the sawchain as in claim 1, in

which the guide slots of the inner cylinder are of difierent width and the ends of the. bolts engaged in these slots are flush with the outside of the inner cylinder. 4. In portable motor tree saws, in comb1- nation a guidingdevice for the saw chain consisting of a guide rail, two chain wheels connecte therewith, one of these chain wheels having means for engaging with the corresponding part of the motor shaft, further a shield placed on one side of the wheel and corresponding to a flange on the motor, thisshield having a bearing for this wheel and being connected to the rail and adapted to be fastened to and above said flangefor the urpose of rendering possible a quick fit of t e unit composed of chain wheels and guide tothe motor as well as a rapid ex- In witness whereof I aflix my signature. FRIEDRICH WILHELM MEYER.

non-return valve, which ojection and the bottom of 

